In a CDMA system, pseudo noise (PN) is offset to be a phase of a short code pseudo random series of 15 bits with the unit being 64 chips. There is a pilot offset increment (PILOT_INC) parameter in the system, where pilot PN (PILOT_PN) of each BS is an integral multiple of this parameter. For example, when PILOT_INC is a default value of 4 for the CDMA protocol, the number of pilot offsets that can be used for assignment is 512/4=128, wherein the pilot offset is referred to as an offset value relative to a zero offset pilot series with the maximum value being 512, and PILOT_PN may be 0, 4, 8, 12, 16 . . . A user equipment (UE) submits a pilot intensity measurement report containing information, such as pilot PN phase (PILOT_PN_PHASE) and its corresponding intensity, to a BS, wherein PILOT_PN_PHASE is a pilot phase with the unit being a chip, measured by a UE under system time. Because of some reasons, such as the existence of signal propagation delay, PILOT_PN_PHASE is not necessary to exactly equal to an integral multiple of PILOT_INC×64, but PILOT_PN should be an integral multiple of the ratio of PILOT_PN_PHASE to PILOT_INC×64, that is, PILOT_PN may be obtained through the following equation:
      PILOT_PN    =                  ⌊                                            PILOT_PN              ⁢              _PHASE                        +                          32              ×              PILOT_INC                                            64            ×            PILOT_INC                          ⌋            ×      PILOT_INC        ,Where “└ ┘” means rounding down calculation. The reason why PILOT_PN_PHASE and 32×PILOT_INC are summed up and then the sum is divided by 64×PILOT_INC is that in view of the possible delay in PILOT_PN_PHASE reported by the UE, a complete PILOT_PN_PHASE will be formed after 32×PILOT_INC is added.
According to the status maintained by the UE, PILOT_PN may be divided into several sets, namely, an activation set, candidate set, neighbor set and residual set. The activation set refers to a set of PILOT_PNs which have been assigned to the UE and are being demodulated; the candidate set refers to a set of PILOT_PNs which have not yet entered into the activation set to be demodulated but reach intensity required for correct demodulation; the neighbor set refers to a set of PILOT_PNs which have not yet entered into the activation set or candidate set but may enter into the activation set or candidate set upon handoff; and the residual set refers to a set of all the other PILOT_PNs except the activation set, candidate set and neighbor set in the system. The UE searches only the PILOT_PNs which equal to an integral multiple of PILOT_INC when searching the residual set. The larger the value of PILOT_INC, the larger the interval between the PILOT_PNs, and the more easily the PILOT_PN of each base station is distinguished, thus, misjudgment of PILOT_PN is not caused easily, but in the meantime the number of PILOT_PNs which can be assigned by the system is less. PILOT_PN resources available for assignment will be less and less with increasing of the number of base stations. A current solution is to use different PILOT_INCs within or between the BSs, that is, in regions where the BSs are distributed more densely, PILOT_INC may be assigned a minor value, such as 2, to obtain more PILOT_PNs available for assignment; whereas in regions where there are less BSs, PILOT_INC may be assigned a larger value, such as a protocol default value 4.
However, in an across-BS handoff process of the existing standard, when a target BS and a source BS are assigned different PILOT_INC information, and when the pilot intensity measurement report submitted by the UE contains PILOT_PN_PHASE under the target BS in the residual set, because the source BS can not obtain the PILOT_INC information of the target BS, the source BS will not be able to calculate PILOT_PN accurately, which will cause failure of handoff, and current traffic of the UE will be interrupted.